Biometric authentication systems are used for authenticating and/or verifying users of devices incorporating the authentication systems. Biometric sensing technology provides a reliable, non-intrusive way to verify individual identity for recognition purposes.
Fingerprints, like various other biometric characteristics, are based on distinctive personal characteristics and are, thus, a reliable mechanism for recognizing an individual. There are many potential applications for using fingerprint sensors. For example, fingerprint sensors may be used to provide access control in stationary applications, such as security checkpoints. Electronic fingerprint sensors may also be used to provide access control in mobile devices, such as cell phones, wearable smart devices (e.g., smart watches and activity trackers), tablet computers, personal data assistants (PDAs), navigation devices, and portable gaming devices. Accordingly, some applications, in particular applications related to mobile devices, may require authentication systems that are both small in size and highly reliable.
Biometric “spoofing” is any attempt to circumvent biometric security using a replica of a user's sensed biometric. In the context of fingerprint authentication systems, some examples of spoofing materials include a three-dimensional (3D) gelatin mold of a finger, a graphite mold of a finger, a wood glue mold of a finger, and printed two-dimensional (2D) image of a finger, among others. In the context of facial recognition, an example spoofing material could be a photo of person's face. In the context of voice recognition, an example spoofing material could be a vocal imitation or playback.
In order to maintain the integrity of biometric authentication systems, there is a need for anti-spoofing systems and methods, also referred to as “liveness detection”, that can detect when an authentication attempt is a spoof and, upon spoof detection, properly deny authentication.